Grafting of aminated oligogalacturonans onto Douglas fir barks. A new route for the enhancement of their lead (II) binding capacities.

Chemical modification of Douglas fir bark and its subsequent utilization in adsorption of PbII from aqueous solutions was investigated. A new approach to enhance the natural properties of bark by covalent grafting of oligogalacturonans was developed. The polysaccharidic moiety of barks was functionalized by periodate oxidation and derivatized after reductive amination in presence of aminated oligogalacturonic acid. PbII adsorption isotherms of derivatized barks were then determined and compared with the capabilities of crude barks using the Langmuir adsorption model in terms of affinity (b) and maximum binding capacities (q(max)). Derivatization resulted in significant enhancements of the q(max) values (up to x8), along with little change of the affinity parameter.

Design and efficient synthesis of a new scaffold based on unsymmetrical protoporphyrin IX derivatives for use in SPPS.

Fmoc-protected amine derivatives of Protoporphyrin IX were synthesized by two original methods using solid-phase chemistry. The new compounds represent unsymmetrical scaffolds suitable for the generation of a large range of peptidic porphyrin derivatives through SPPS strategy.

Solvent-controlled regioselective protection of 5'-O-protected thymidine.

This paper describes an efficient procedure for selective 3'-O- or 3-N-protection of 5'-O-tert-butyldimethylsilylthymidine, depending on the use of aprotic polar solvents with low or high dielectric constant, respectively. These syntheses were activated by either ultrasound or microwaves. Several alkyl bromides offer a convenient route to prepare 3'-O- or 3-N-protected and functionalized thymidine derivatives.

Glycosyl bis-porphyrin conjugates: synthesis and potential application in PDT.

Syntheses of new glycosylated neutral and cationic porphyrin dimers linked at the meso-position via a flexible hydrocarbon chain are described. A detailed 1H and 13C NMR study allows their complete structural elucidation. The UV-visible, fluorescence and MALDI mass spectra are also presented. Photocytotoxicities of these compounds against K562 leukaemia cell line are compared to those of Photofrin II.

Amino porphyrins as photoinhibitors of Gram-positive and -negative bacteria.

Twenty four aminoporphyrin derivatives have been tested in vitro for their antibacterial photoactivity against Escherichia coli and Staphylococcus aureus. Two of these compounds, bearing polyamine units, exhibited a significant activity especially against Gram-negative bacteria (E. coli).

Synthesis and biological evaluation of thioglycosylated porphyrins for an application in photodynamic therapy.

The aim of this work is the synthesis of a new family of glycosylated porphyrins in which the sugar moieties are linked to the tetrapyrrole ring by a thioglycosidic bond. Two series have been designed. The first one corresponds to meso-aryl porphyrin derivatives. The second one has been obtained from protoporphyrin IX derivatization. Aryl-porphyrins were prepared from tristolyl o- and p-hydroxyporphyrins followed by bromoallylation and thioglycosylation with peracetylated S-glucose, mannose and galactose and deprotection. The other series has been synthesized from protoporphyrin IX dimethylester with a regioselective glycosylation of terminal alkenyl carbon. The UV-visible, NMR and MALDI mass spectra are presented. Photocytotoxicities of the synthesized compounds against K562 chronic leukaemia cell line has been evaluated.

Field- and flow-dependent trapping of red blood cells on polycarbonate accumulation wall in sedimentation field-flow fractionation.

Sedimentation field-flow fractionation (SdFFF) instrumentation is now mature. Methodological procedure and particle separation development rules are well established even in the case of biological species. However, in some biological applications, retention properties of samples not predicted by any field-flow fractionation (FFF) elution models are observed. It is demonstrated that the trapping of cellular material in the separation system is not related to geometrical instrumentation features but to channel wall characteristics. The physicochemical particle-wall attractive interactions are different depending on the flow-rate and field intensity applied. Separation power in SdFFF for biological species is therefore limited by the intensity of these interactions. In terms of separation, a balance is to be found between external field and flow intensity to limit particle-wall interactions.

Fungicidal properties of meso-arylglycosylporphyrins: influence of sugar substituents on photoinduced damage in the yeast Saccharomyces cerevisiae.

A series of neutral meso-arylglycosylporphyrins has been tested in order to evaluate their potency as antifungal agents against the yeast Saccharomyces cerevisiae. Photodynamic activity of these molecules results in intracellular damage as evidenced by the loss of clonogenicity and DNA fragmentation. The ability of these photosensitizers to permeate yeast cells is determined by microspectrofluorimetry and is correlated with their antifungal potency. Amphiphilic porphyrin derivatives are shown to exhibit the more pronounced photoactivity.

Chronology of the apoptotic events induced in the K562 cell line by photodynamic treatment with hematoporphyrin and monoglucosylporphyrin.

Photodynamic treatment of promyelocytic K562 cells in the presence of a monoglucosylporphyrin or hematoporphyrin leads to a sequence of events recognized as hallmarks of apoptosis: a drop in mitochondrial potential, concurrent with a drop in ATP level and a decrease in cell respiration, translocation of phosphatidylserine of the plasma membrane, DNA fragmentation, appearance of apoptotic bodies and eventually loss of plasma membrane integrity. The chronology of these events is in accordance with sequential events induced by other known proapoptotic agents; in contrast to these agents that induce apoptosis in a restricted part of the cell population, we observed that the entire cell population (apart from a small percentage of cells that endured rapid necrosis during phototreatment) underwent apoptosis after irradiation in the presence of porphyrins. It appears that photodynamic treatment allows the bypass of early apoptotic signals in K562 cells that are otherwise renowned for their resistance to drug-induced apoptosis (A. McGahon, R. Bissonnette, M. Schmitt, K. M. Cotter, D. R. Green and T. G. Cotter, Blood 83, 1179-1187, 1994). Singlet oxygen is believed to be the proximate reactive species generated by porphyrin illumination. Because this molecule reacts with almost every cellular constituent, the way that singlet oxygen or its reactive oxygen species byproducts trigger apoptosis remains to be elucidated.

Synthesis and antiviral evaluation of pyrazinones substituted with acyclic chains.

The synthesis of a series of pyrazine analogues of the anti-herpes compound, acyclovir is described. These syntheses were accomplished by various methods: in the presence of a Lewis acid or NaH for hydroxyethoxymethyl and hydroxybutyl groups or by sequential oxidation/reduction of 1-(beta-D-ribofuranosyl)-2-pyrazinones for 2',3'-acyclonucleosides. Antiviral (HSV-1, CMV, Cox B4, HIV-1) properties of these compounds were determined.

Potential antiviral agents. Part II. Synthesis and antiviral evaluation of pyrazinones substituted with acyclic chains.

The synthesis of a series of 4'-substituted hydroxybutyl pyrazine analogues of the anti-herpes compound, acyclovir, is described. The compounds were characterized with 1H and 13C nmr, mass and IR spectroscopy. Antiviral (HSV-1, CMV, Cox B4, HIV-1) properties of these compounds were examined. None of these compounds were active against these viruses.

Nitroglycosylated meso-arylporphyrins as photoinhibitors of gram positive bacteria.

Novel porphyrins bearing nitro groups and glucosyl moieties were synthesized. The antibacterial activity of these compounds on Escherichia coli and Staphylococcus aureus is described. Results reveal that their photocytotoxicity is markedly dependent on the nature, the number and the linking position of the glycosyl moieties and nitro groups controlling their amphiphilic characters.